Rotary cutter assembly



April 1970 R. M. GREENBERG 3,507,180

ROTARY CUTTER ASSEMBLY Filed Oct. 11, 1967 2 Sheets-Sheet L P90 Afar I i E]. i 4 T INVENTOR. T q BY FOBERr f2 G EQ B I G April 21, 1970 R. M. GREENBERG 3,507,180

RQTARY CUTTER ASSEMBLY Filed Oct. 11, 1967 2 Sheets-Sheet 2 INVENTOR. 4 1 7 @PEZABEW BY 7% W 47 0 N65 United States Patent f 3,507,180 ROTARY CUTTER ASSEMBLY Robert M. Greenherg, New York, N.Y., assignor to Phoenix Works, Inc., New York, N.Y., a corporation of Delaware Filed Oct. 11, 1967, Ser. No. 674,559 Int. Cl. B26d /08 US. Cl. 83-592 5 Claims .ABSTRACT OF THE DISCLOSURE A rotary cutter head with peripherally extending knives in which mounting slots for the knives are disposed in the head in a skew relationship to the rotary axis of the head and the knives have straight shank portions residing in the slots and fastening means are provided for longitudinal adjustment of the knives in the slots to compensate for wear on the cutting edges of the knives. The knives have angular cutting edges which provide a slicing action and provide for cutting of equal lengths of fiber material or the like conveyed through the cutting plane of the rotating knives.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a novel rotary cutter assembly having particular adaptability for cutting fiber tow material into equal staple lengths and more particularly to such an assembly for use in the cutting of polyester staple fibers.

Description of the prior art Heretofore in the cutting of staple fibers in, for example, polyester plants it has been the practice to use a rotary cutter head assembly employing knives having shank portions disposed in radial slots in the cutter head disposed symmetrically in the cutter head. Each knife had a shank portion which was fastened in the slot and then had a blade portion thereof extending from the shank portion at an angle thereto.

With the prior art design the cutting edge of the blade engaged the tow to be cut in a fiat or parallel relationship so that rather than a slicing action of the cutting edge on the tow, it involved more of a chopping effect which frequently by itself resulted in unequal staple lengths. Furthermore, as the cutting edges became dull and the knives were sharpened individually, it was difv ficult, if not impossible, to maintain a dynamically balanced cutting head and a constant distance between adjacent cutting edges of the knives, which factors also resulted in cutting of unequal staple lengths. The prior art blades had a tapered cross section which, during successive sharpening resulted in decreased blade strength and enhanced blade and edge fracture during use. Successive sharpening also resulted in a weakening of the blade portion at the junction with the handle because of the notch effect. Blade fracture also was enhanced by the chopping cut itself.

Therefore the prior art is characterized by cutter assemblies which not only resulted in variations in staple lengths, which is undesirable, but also resulted in an increased cost of operation in view of the frequent blade breakage and requirement of blade replacement, and excessive grinding to remove edge fractures.

SUMMARY OF THE INVENTION Briefly, the present invention involves a rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths, fiber material Patented Apr. 21, 1970 being passed substantially perpendicular to the plane of rotation of the assembly. The assembly includes a circular base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to the plate. The base plate includes a plurality of symmetrically disposed chordal slots extending to the periphery of the base plate. Blades having straight shank portions are disposed in the slots and mounting means is provided for adjustably positioning said shank portions longitudinally relative to the slots. The blades include straight outer extensions of substantially uniform cross section joined to said shank portions and being disposed outwardly from the periphery of the base plate with angular cutting edges thereon. The angular distance between the cutting edges of adjacent blades is substantially uniform throughout the assembly.

With the above device it is now possible to cut a continuous polyester tow into guaranteed staple lengths for indefinite periods of time. The angular cutting edge of the blades provides a slicing cut, as opposed to a chopping cut, and not only assists in achieving equal staple length but also minimizes blade breakage due to the elimination of the impact force of a straight edge against the entire side of the tow as in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features of the present invention will appear in the following description and claims and in the drawings in which: 1

FIG. 1 is a front elevation of a typical prior art assembly;

FIG. 2 is an enlarged section taken along line 22 of FIG. 1;

FIG. 3 is a front elevation of a cutter assembly according to the present invention;

FIG. 4 is an enlarged section taken along line 4-4 of FIG. 3;

FIG. 5' is an enlarged exploded fragmentary isometric view of a knife assembly as shown in FIG. 3;

FIG. 6 is an enlarged fragmentary view showing a knife of the present invention in cutting position with respect to a fiber tow; and

FIG. 7 is an enlarged fragmentary view showing a knife of the prior art in cutting position with respect to a fiber tow.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, FIG. 3 shows one embodiment of the present invention in which the cutter head assembly is designated generally by reference numeral 10 and comprises a circular base plate or disc 11 having central bore 12 adapted for mounting on a conventional rotary shaft (not shown). A plurality of knives 13 are disposed in a symmetrical fashion on the base plate as shown. Each knife 13 has a straight shank or handle portion 14 and a blade portion 15 having a rear or noncutting edge 16 extending straight from the shank portion 14 and a front or cutting edge 17 extending outwardly at an angular relationship to the shank portion 14 as shown in FIG 3. (see also FIG. 5). Each shank portion 14 is mounted in a respective slot or groove 18 in base plate 11 which is disposed along a chord of the circular base plate, i.e., it is disposed in a skew relation to the axis passing through bore 12 of the base plate 11. Each slot has a plurality of threaded mounting holes 19 disposed longitudinally along the slot 18 to provide in conjunction with screw means 20 and hole 20a in handle 14 means for affixing the knife 13 to the base plate 11. The plurality of holes 19 provides for longitudinal adjustment of the knife 13 relative to the base plate 11 and permits compensation for wear on the cutting edge 17 which will be described in greater detail hereinafter.

FIG. 4 shows the cross-sectional configuration of the blade portion which is more or less uniformly tapered throughout its length and because of the flat sides permits the entire blade assembly to be sharpened as a unit without disassembly.

The prior art device is shown in detail in FIG. 2 wherein the base plate 24 has a plurality of radial slots 25 each carrying the shank portion 26 of knife 27, the latter having an angular blade portion 28 in which the front cutting edge 29 and rear non-cutting edge 30 are disposed at an angular relationship to the shank 26. Mounting screw means 31 affixes the knife to the base blade. No adjustability is provided longitudinally of the slot 25 now could it be due to the angularity of the blade. As shown in FIG. 2 the cross-section of blade 28 is generally curved which requires disassembly of the blades for individual sharpening with the consequent likelihood of non-uniformity of blade configuration.

In use in a conventional fiber line (see FIG. 6) the tow 21 of polyester or the like is fed perpendicularly through the cutting plane of knives 13 between adjacent fingers 22 of rubber wheels 23 (shown partially) and the blade assembly is rotating in the direction of arrow B to bring cutting edge 17 of blade 15 into engagement with tow 21 in the angular relationship shown which provides a slicing action of the tow rather than the chopping action shown with the prior art blade 27 (FIG. 7) caused by the parallel relationship of the cutting edge 29 and the flat side 32 of tow 21 held between rubber wheel fingers 22.

The present novel design provides a means of establishing standards of staple length which can remain fixed and absolute which would not be altered or changed as the result of resharpening, oversharpening, single or multiple blade replacement, sequence of starting the grinding cycle, number of passes across the grinding stone, depth of cut, et cetera. The head is adapted to be mounted on a companion automatic grinder which grinds the six blades sequentially and without being removed from the mounting head.

As the cutting edge 22 of the blade of the present invention is sharpened (see dotted lines of FIG. 6) the cutting angle relative to the face of the tow remains fixed throughout whereas the successively and individually sharpened cutting edge of the prior art blade can present an increasing and/or changing angle to the tow and as a result with the blade of the present invention fixed and uniform distance between the cutting edges of adjacent blades in the assembly is maintained whereas it is obvious that variations in such distance are virtually inherent in the prior art device. Furthermore, sharpening of the prior art device creates a notch 32 at the junction of the handle 26 and blade 28 at the cutting edge 29 which results in mechanical weakening due to the notch eifect and increased tendency to break during use.

The longitudinal adjustability of the knife of the present invention in its slot permits adjustment for Wear and resharpening and more complete utilization of the knife thereby providing longer life and reducing the cost of operation.

The device provides guaranteed staple lengths for indefinite periods of time, elimination of unequal staple length, minimization of blade breakage, minimization of edge fractures due to impact, provides a ninety percent consumable blade, elimination of large blade inventory, a dynamically balanced head at full rotary speed, use of a blade of uniform cross section and a slicing cut as opposed to a chopping cut.

While one embodiment of the invention has been shown and described it is to be understood that changes and additions may be made by those skilled in the art without departing from the scope and spirit of the invention.

I claim:

1. A rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths fiber material being passed substantially perpendicular to the plane of rotation of said assembly, said assembly including a base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to said plate, a plurality of symmetrically disposed slots in said base plate disposed in a skew relation to said axis extending to the periphery of said base plate, said blades having straight shank portions of complementary shape relative to said slots and straight outer extensions including cutting edge portions having substantially uniformly tapered lateral cross-sections, said shank portions being disposed outwardly from the periphery of said base plate, and mounting means for adjustably positioning said blades longitudinally relative to said slots.

2. A rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths fiber material being passed substantially perpendicular to the plane of rotation of said assembly, said assembly including a base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to said plate, a plurality of symmetrically disposed slots in said base plate disposed in a skew relation to said axis extending to the periphery of said base plate, said blades having straight shank portions of complementary shape relative to said slots and straight outer extensions including cutting edge portions having angular cutting edges and substantially uniformly tapered lateral cross-sections, said shank portions being disposed in said slots with said extensions disposed outwardly from the periphery of said base plate, and mounting means for adjustably positioning said blades longitudinally relative to said slots.

3. A rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths fiber material being passed substantially perpendicular to the plane of rotation of said assembly, said assembly including a base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to 'said plate, a plurality of symmetrically disposed slots in said base plate disposed in a skew relation to said axis extending to the periphery of said base plate, said blades having straight shank portions of complementary shape relative to said slots and straight outer extensions of substantially uniform cross section including cutting edge portions having angular cutting edges and substantially uniformly tapered lateral cross-sections, said shank portions being disposed in said slots with said extensions outwardly from the periphery of said base plate, and mounting means for adjustably positioning said blades longitudinally relative to said slots.

4. A rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths fiber material being passed substantially perpendicular to the plane of rotation of said assembly, said assembly including a base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to said plate, a plurality of symmetrically disposed slots in said base plate disposed in a skew relation to said axis extending to the periphery of said base plate, said blades having straight shank portions of complementary shape relative to said slots and straight outer extensions of substantially uniform crosssection including cutting edge portions having angular cutting edges and substantially uniformly tapered lateral cross-sections, said shank portions being disposed in said slots with said extensions disposed outwardly from the periphery of said base plate, the angular distance between the cutting edges of adjacent blades being uniform throughout said assembly, and mounting means for adjustably positioning said blades longitudinally relative to said slots.

5. A rotary cutter assembly having a plurality of aligned blades adapted for cutting into predetermined equal lengths fiber material being passed substantially perpendicular to the plane of rotation of said assembly, said assembly including a circular base plate having centrally disposed means for mounting said base plate for rotary motion about the axis perpendicular to said plate, a plurality of symmetrically disposed chordal slots in said base plate extending to the periphery of said base plate, said blades having straight shank portions of complementary shape relative to said slots and straight outer extensions of substantially uniform cross-section along their lengths including cutting edge portions having angular cutting edges and substantially uniformly tapered lateral crosssections, said shank portions being disposed in said slots with said extensions disposed outwardly from the periphery of said base plate, the angular distance between 6 the cutting edges of adjacent blades being uniform throughout said assembly, and mounting means for adjustably positioning said blades longitudinally relative to said slots.

References Cited UNITED STATES PATENTS JAMES M. MEISTER, Primary Examiner US. Cl. X.R. 83355, 700, 913 

